Turbulence and combustion-promoting device for ram jet motors



Dec. 7, 1954 F. WEEKS TURBULENCE AND COMBUSTION-PROMOTING DEVICE FOR RAM JET MOTORS Filed Nov. 2a, 1949 United States Patent O TURBULENCE AND COMBUSTION-PROMOTING DEVICE FOR JET MOTORS I Ivan F. Weeks, Altadena, Calif., assignor to the United States ofl America asvrepresented by the Secretary of the Air Force The invention described herein may be manufactured and used by or for the Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to a turbulenceand combustionpromoting device for use in ram-jet motors to furnish the driving power thereof.

One object of the invention is to provide a simple means of mixing and burninghydrocarbon fuel and air together under conditions promoting intense and complete combustion.

Another object is to provide a light, simple and ehicient driving means for ram-jet motors.

Another object is to provide means for burning hydrocarbon fuels of a liquid nature in ram-jet motors which would otherwisev be too diicult of combustion to be so employed.

Briey stated, -this invention comprises a straight tube substantially open at both ends which is provided with particularly efficient means, either internally or at the rear end thereof as mounted in the ram-jet motor, for mixing and burning a stream of hydrocarbon spray or vapor with air. One form of the invention employs a ceramic helix within the tube; a second form employs a perforated metallic cage mounted on the rear end of the tube, said cage being provided with an after-cone; a third form employs a rearwardly tapered metallic perforated cage mounted adjacent the rear end of the tube and inclosing the latter.

Referring now to the drawing:

Fig. 1 is a side elevation partly in section, of a ramjet motor showing a plurality of my devices mounted in circular fashion on the internal wall of the motor;

Fig. 2 is a longitudinal section of my device in its preferred form showing therein a ceramic helix which is not sectioned;

Fig. 3 is another modification of my device showing an unsectioned rear end of a tube and mounted thereon, a sectioned perforated metallic cage in the after-end of which is mounted a perforated metallic cone shown partly in section; and

Fig. 4 corresponds to Fig. 3 but in this modification the perforated metallic cage has a rearwardly narrowing taper and a shape of a frustrum of a cone. It is shown sectioned.

Referring again to Fig. l, is a ram-jet motor which comprises an outer shell 11 and inner shell 12 spaced therefrom and substantially circular thereto. The shell has the conventional form of a ram-jet motor which has a forward center opening 13 and is streamlined, an ellipsoidal body 14 mounted therein by struts 15 to dene an annular passage 16 for the admission of air. Mounted within the annular passage 16 there is a circular manifold 17 having thereon a multiplicity of fuel nozzles 18 which have equal spacing and face toward the rear of the shells 11 and 12. No novelty is claimed for the construction of the ram-jet insofar as its shell arrangement, fuel nozzles and air passages is concerned. Mounted by means of brackets 19, a plurality of my turbulenceand combustion-promoting devices 20 are attached longitudinally, the inner surface of the inner shell 12 approximately amidships of the motor. The The devices are preferably mounted equal distances apart substantially parallel to the middle portion of the shell 12 and to each other and a substantial distance behind the nozzles 18. The object of such spacing is to provide suflicient space for preliminary mixing of hydrocarbon fuel and air in the space 21 between the nozzles Patented Dec. 7, 1954 ICC ` 18 and my devices20. Each device 20 as will be seen in both Figs. 1 and 2, is provided` with a spark plug 22 or other ignition device which extends through the innerv shell 12 and which is preferably protected from heat by a refractory collar 23. As shown in Fig. l, there may be one or more llame-transfer tubes 24 extending between the devices 20 to provide intercommunication between the tubes 25 of said devices to promote fast flame propagation during the ignition stage. The llame transfer tubes are, however, strictly not necessary and may be omitted.

passage of flaming gas.

Referring now particularly to Fig. 2, within the tube 25 there is a closely fitting ceramic helix 26 having a deeply grooved spiral passage 27 of comparatively large cross section, so as not to offer undue resistance to the The passage of groove 27 may have a different shaped cross section from the oneshown, since the shape is not critical. lt is to be observed that the spark plug 22 is so mounted that its electrodes are in communication with and project into the groove 27.

The helix 26 is made of refractory ceramic material which may, for example, be pure silica such as diatomite, plus a fire clay binder, or it may be made of silicon carbide, or aluminum oxide or magnesium oxide, or zirconium oxide or, in general, any high grade, mechanicallystrong refractory material which will not soften below 2400 C. For purposes of promoting combustion, this refractory body has preferably a reasonably roughV surface and its mass or surface may be impregnated with combustion-promoting catalysts such as the oxides of manganese, cerium, vanadium, uranium, or mixtures thereof. The exact proportion of catalyst is not critical, but in general it should not be less than approximately 3% by weight of the ceramic mass on a dry basis.

The inner end 28 of the ceramic body 26 is preferably somewhat extended or unfolded as shown in Fig. 2 -so as to offer easy ingress into the groove 27 for the gases which enter and leave the tube as shown by the arrows in Fig. 2. A retention means 29 is shown extending through the tube 2S and the ceramic helix 26. As many of these retention means as is necessary may be employed and other retention means may be used as distinguished from the particular form shown. It is evident that a mixture of hydrocarbon spray or vapor and air entering the tube 25 in Fig. 2 as indicated by the arrows will be swirled by the helix 26 through the groove 27, ignited by the spark plug 22 and brought into intimate contact with the combustion promoting ceramic body with or without catalysts and so thoroughly mixed so that substantially perfect combustion is achieved and that a maximum of power will be developed at the exit end 30 of the combustion and turbulence promoting device. lt is necessary of course, and contemplated by this invention that enough combustion air will be supplied by the pase sage of the ram-jet motor 1t) through the atmosphere to provide enough oxygen for complete combustion.

Referring now to Fig. 3, a thin metallic shell 31 is strongly attached to the rear end 30 of the tube 25 by means of bracket or other holding device 32. The shell 31, which is preferably made of nickel-chromium alloy, is provided with a multiplicity of regulated spaced perforations 33. The perforations of the length and diameter of the shell 31 may be varied, but in general will not be less than 10 inches, nor more than 3 feet long. At the rear end of the shell 31 there is inset by means of brackets 32 a hollow cone 34, likewise made of thin nickel-chromium alloy. It also bears a multiplicity of perforations 33. The base diameter of the cone should be approximately that of the internal diameter of the shell 31. Suflicient egress space for the llame should be left at 35 to enable a substantial part of the flame to escape without going through the cone. A high velocity ame ejected from the rear end 30 of tube 25 will create an aspirating elect within the shell 31 and draw in additional air through the perforations 33 of the shell and also to a certain extent through the perforations 33 of the cone 34, thereby promoting combustion by boosting the flame and giving additional thrust.

Referring now to Fig.`4, the shell 31 in this modiication has a frustro-conical shape, the narrower end thereof being aft of the tube exit 30. Its perforations 3`3` are relatively larger than those of the form shown in Fig; 3, since theshellv asal Whole-issomewhat smaller' than that shown in Fig. 3` and therefore sucient air must be drawn in a shorter period of time than is available: when .the form ,shown .ini-Fig. 3 is used; However,` a., substantial. aspirating effect; is: also. available inl thisy form'. around. the. bracket or clamp32,.past1which aird mayy stream. intov the shell. 315.. tl'iroughl a. passagel 36?- formed betweenv the tube. endf 30'- in` the internal Wall of the.. shell. A substantial. admix-ture. of airisuobtainedl to promote. afterburning, evenwith ashort shellf3'1t, onx account-of` the highvelocity. of the burninggases stream-- ing therethrough..

f Numerous-.modificationsof. thisy device. may besmade Without departing from the spirit of the invention; For example, the. tubes 25: need notbecylindrical as shown but may,I be square or. polygonal. The. same-is'true ofI the: shells. 31. If. such tube. shapesare. used,.the shape ofthe ceramic helix 26 would.` of.-I course. be varied? to conform tothe `shape of .the tube interior.,

The use of. any formofI this invention in a: ram-jet.` motorhas asalutary, effect in preventing.. extinction of the name..

What Iclaim is:

1; In a combustion tube for a ram-jet motor, astraight tube open at both ends mounted therein: withits. axis arranged parallel to the. longitudinal. axis=of the combustion tube and. positioned. in the path. ofi ignitable. gases flowing through4 saidcombustion tube, afrefractoryy ceramic body within said straight'. tube,.said. body. providinga continuous helical passageA from one. ofits ends. tothe other adapted to swirl and pass a substantial volume of gas between said bodyA and' said straight tube,.

and ignition means operatively mounted to extend :through the. Wall of said straight tube into said helical passage at a point intermediate the ends of. theceramic body.

2. In a combustiontube:for'aram-jet motor, a straight.

tube open at both ends mounted.` therein with its axisl arranged so as tobe parallelto the longitudinal axis of the combustion tube andipositioned in the pathof ignitable gases flowing through said combustion tube, a refractory ceramic` body havingan outer diameter.: approximating the bore of the straight tube retained. in saidy straight tube, the body beingv inthe forrrpof an openv ended helix and havinga helical spiral passage.` about.

project into saidhelical passage.

3. In a combustiontubefor a ram-zjetrnotor, .a straight tube` open at. both ends mountedtherein in the.pathv ofignitable gases flowing. through. they combustion tube,` combustion promoting means mounted inA said straight.

tubeproviding a devious passage therethrough,.ignition. means mounted in the Wall of. said tube. andfextending:

into. said passage intermediate its. ends,.secondaryl corn'- bustion promoting means attached to said straight: tube:- forming an extension thereof, said secondary combustionv promoting means` including a multiperforated` cylinder 4:' mounted on the discharge end of said straight tube providing anA extension thereof` and' a' conicalmemberl mounted in the end of the cylinder and having its outer surface spaced from the inner wall of the cylinder whereby to promote afterburning.

4. In a combustion tube for a ram-jet motor, a straight tube open at bothy ends mounted therein in the path of ignitable gases flowing through the combustion tube, combustion promoting means mountedin said straight tube providing ay deviousrpassage therethrough, ignition means-mounted' in'. the wall of said tube andl extending into said passage intermediate its ends and secondary combustion promoting means attached to said straight tubeforming any extension..thereof,.said. secondary combustion promoting means being of frustro-conical shape, the wider end ofi said secondary combustion promoting meansinclosing and beingattached to a short portion of the'end of the straighttube.

5. Aram-jet motor comprisingy a hollow shell definingan air inlet4 at its forwardend, means for injecting, fuel therein connectedto. the. forward end of said she1l,'.

a plurality of spaced straight tubes` arranged centrally of the. shell with their vaxes-parallel. toI theu longitudinal-l axis of the shell and in the pathfof4 the ignitable gases.

flowing through the. shell, a ceramic body mountedA in each of. said straight` tubes. providing a devioustpassage,

therethrough.. ignition. means extending into at leastv one of said tubes in the passage intermediate thel ends.thereof ame transfer tubes interconnecting said straight tubes,

and'a flame holdingmeansassociated witheachof saidy straight tubes.

6. In-a combustion tube for a ram-jet motor', a. pluralityfofstraighttubes open at bothends mounted therein, with their axes arranged substantially parallel to the axis'` of the combustion tube, acombustiontpromotingmeans in each straight tube providing a deviouspassage therethrough and in the path of ignitable gases Iflowing through; the combustiontube, ignitionmeans mounted in theV Wallofy one of said straightl tubes and extending. into the passageprovided therethrough and ame transfer tubes interconnecting said. straight tubesfor flame propagation.

References Cited'in thezleof this patent UNITED STATES PATENTSl 

